Refrigerating mechanism



Sept. 8, 1942. G. MUFFLY IUSERIGRA'TING MECHANISL;

3 Shasta-Sheet 2- Filgd ny "25, 1937 Patented Sept. 8,A 1942 UNITED STATES PATENT OFFICE a Y l 2,295,124- l REFRIGERATDIG MEcnANrsM Glenn springend, ohio Application May 25, 1 937, Serial No.'144,698

vision of a gear pump so constructed and ar- 19 Claims.

This invention relates' to refrigerating mechanisniV and has` for -its principal object the provision of a mechanism of this type that is simple in construction, efficient. in` operation and economical to produce.

Other objects of the invention include the pro- T vision of a sealed type of refrigeration unit embodying certain novel features of construction;-

is open to the interior of the sealed unit; the pro-` vision of a refrigerating mechanism including a refrigerant circuit at least part of which comprises'a plurality of refrigerant paths connected in parallel'anda novel form of means for alter- A nately opening sndclosing said paths to the flow of refrigerant therethrough; `the provision of a Cil ranged as to provide for maximum accuracy 'in 'ence'to' the accompanying drawings, and then claimed; having the above smoother objects in view. l f

In the accompanying drawings which illustrate a suitable embodiment 'of the present invention and in which like numerals refer to like parts 'throughout the several different views:

r Figure 1 is a more -or less diagrammatic view Y of a refrigerating mechanism embodyingfeatures refrl'gerating mechanism as above described in which the controlling means for the parallel paths of'refrigerant flow are contained within a sealed refrigerant motor-compressor unit; the vprovision of arefrigerating mechanism including a refrigerantcirculatory system at least part of which comprises a plurality of refrigerant iiow paths connected in parallel and fed with refrigerant through a single expansion valve together with means for maintaining the suction pressure in one of the parallel flow paths at a `lower value than in another thereof; the provision of a refrigerating'mechanis'm having a novel form o'f means associated therewith serving to provide a compressor unloading eifect therefor whereby to enable a smaller driving motor to be utilized than would otherwise be possible; and the provision of a new and novel form of olling mechanism fora the provision of.a new and novel form of gear pump; the provision of a refrigerant compressor a gear pump havinginvolute teeth and so4 constructed and arranged as to provide a pump of high'eiliciencyv that-is economical to manufacture; the provision of a gear pump particularly for refrigerating mechanism providing a plurality of independent suction passages capable of operating under diierent suction-pressures,

and a commondischarge passage; the provision of a' gear pump particularly adapted for the comr`f-pressiorrof gases including` gears having a novel form of co-operating teeth thereon; and the pro lline 3 3 thereof;

and'outlet passages for the of the present invention;

Flg.,2 is an enlarged, partially broken, vertical sectional view taken centrally through a motorv compressor unit const cted in accordance with the present invention and of the type adapted for use in the refrigerating system illustrated in Fig. l;

' Fig. 3 is a partially broken transverse sectional view of the unit'shown in Fig. 2 taken as on the .I Fig. 4 is a transverse sectional view`taken' on theline 4 4 of Fig. 2;

Fig. 5 'isan enlarged fragmentary vertical sectional view taken on the line 5*-5 'of Fig. 3 and illustrating in greater detail the snap switch mechanism for'alternately opening and. closing parallel refrigerant now paths of one portionof the system;

Fig. 6 is an enlarged horizontal sectional view taken on the line S-G of Eig. 2,-illustratin'g inlet pump mechanism located inthe unit;

Fig. 7 is an enlarged fragmentary vertical seci tional view taken on the line 1-1 of Fig.v 4;

Fig. 8 is an enlarged fragmentary' verticalsec-' v uona1 view taken on the une s-a of Fig. 4; l

Fig. 9 Ais a more or less diagrammatic view i1- lustrating ingreater detail the particular` shape and arrangement of the teeth of tries-.gears in the compressor unit; and

Fig. 10 is a fragmentary, vertical `sectional' view of a modied -form of'construction. Although certain features of the present in'- vention arel applicable to refrigerating. systems of more .or less conventional type, certain features thereof in particular-are specially adapted foruse infconnectionlwith refrigerating systems cf the typeshown in my Letters Patent of the United States for improvements in Refrigerating mechanism, Nos. 2,145,773; 2,145,774; 2,145,775 and 2,145,777, all issued January 31, 1939. In my co-pending applications above identified means are shown providedforalternately refrigerating different groups of ic making surfaces whereby to cause ice to be formed alternately by said groups and which ice is adapted to be melted free of its surfaces during that time,

when it isnot being refrigerated and during which time another group of ice making surfaces is being refrigerated.' In my prior applications above referred to these ice making surfaces are positionedwithin an. insulated cabinet wherein the air within the cabinet is adapted to contact a water tank and certain of the refrigerated surfaces of the mechanism and to be cooled to a desirable degree thereby for the proper preservagroup of ice making surfaces for the purpose of freezing the water into ice. Each of the evaporators 40 is provided with -a discharge duct 42 each of which terminates independently of the other thereof within the housing 20.

Within the housing. a valve'mechanism indicated generally at 44 in Fig. 1 is provided for alternately closing the discharge ends of the tubes 42 to the ow of refrigerant therethrough and suitable mechanism is provided, as will hereinafter be specifically described in connection with other views of the drawings for operating the valve mechanism 44 at timed intervals to alternately close and open the ducts 42 thereby to render the evaporator connected with the closed duct inoperative for refrigerating purposes and refrigerated at any particular moment is shown as also passing through an evaporator associated witha chamber positioned within the refrigerator cabinet and itself insulated against exchange of yheat with the bulk of rthe air within the cabinet whereby to provide a sub-freezing chamber or the like. In accordance with the present invention the alternately refrigerated evaporators of a similar ice maker are similarly positioned v to also cool the air within the cabinet but instead of lemploying the refrigerant `p`assing therethrough to produce a refrigeratingeifect in a sub-freezing chamber within the cabinet,l a refrigerant .path of 'ow parallel to the path of fiow to the ice maker is provided-for the sharp freezing (sub-freezing) hamber and, as in my prior constructions, 'the arp freezing chamber is preferably itself insulated from the exchange of heat between the air withinsit and that contained generally within the main food storage space of the refrigerator cabinet.

LIn order to more fully explain this system reference may be had to Fig. 1 in which the numeral 20 represents the housing of a sealed motor-comnismv generallyl indicated at 22 which, in the broader aspects of the present invention, may be of any suitablel type but a specificform v'of which is more fully described in connection with the remaining views forms an important feature of the present invention. The pump 22 is provided with a single refrigerant discharge line 24 which leadsinto the bottom of acontainer 26 the upper end of which' is connected to a conventional type of condenser28 provided with a conventional l receiver 30 at its'lower edge. A tube 32' connects the receiver 30 with asingle expansion valve 34. Although the Ydischarge side of the expansion valve 34 may be connected to any suitable evaporator suitably arranged in co-operative relation with respect to a'water container for causing ice to be formed therein, or employed for` any other purpose, in order to illustrate the application of the presentinventionjto structures of the genpressor unit enclosing a suitable pump mechapurposes.

rendering the evaporator 40 connected with the f open duct open to the flow of refrigerant therethrough and thereby operative for refrigerating As previously mentioned the compressor 22 is provided with a pair of independent suction ports one of which is open to the interior of the housing 20 and acts to withdraw refrigerant from the interior of the housing 20 and consequently from that evaporator -then opened into the interior thereof, such refrigerant being drawn into the pump 22 to be compressed and then dis-4 charged through the outlet duct or discharge line 24.

It willbe understood that the evaporators 40 are positioned within an insulated cabinet indicated' at 50 and exposed to contact with the air therein for the purpose of cooling such air therematter of illustration as either one or the other thereof will be employed, but not necessarily both at one time. 'I'he weighted valve is preferred as it always imposes a predetermined additional pressure reduction to the evaporator 54.

With the construction thus far described it will be understoody that refrigerant fed through` the single expansion valve 34 is fed to either` one or the other ofi-the evaporators 40\as well as to the evaporator 54 and in view of the fact that the pump 22, as will hereinafter 'be more fully described, is constructed to subject the evaporators 40 to a suctionpressure entirely independently of the suction pressure applied to the evaporator 54 and, because of the restriction 58 or 60 in the feed line to theevaporator 54, the suction pressure of the pump applied to the evaporator 54 will be lower than that applied to theN evaporators and consequently the evaporator -54 will be maintained at a lowertemperature 1than the temperatureof the evaporators 40 thereby v-to permit the interior of the chamber 52 to be maintained at a substantially lower temper-` ature than the interior of th'e cabinet 50. .As a

matter of illustration it may be assumed that the temperatureof the chamber 52 may be maintained somewhere between \zero and plus 10 F.,

that the interior of tire-cabinet so may .be maintained at a. temperature somewhere-between '40 to 45 F. and that the evaporators 40 will be main-j tained during their respective refrigerated periods .possible where it is also possible to maintain the suction pressure on the various evaporators at diiierent values.

Another feature of the present invention is the provision of the chamber 26 between. the outv drawings and particularly to Fig. it will be noted that the compressor unit includes the inl verted generally cup-shaped pressed metal housing 20, the lower end of which is closed by the round base member 80 of the pump 22 and` which is hermetically /sealed thereto as by welding along the aligned lower edges. thereof as at 82, or otherwise. Within the housing 20 and seated upon the base 80 is an intermediate pumpubody let side of the compressor 22 and the condenser 28. The chamber 26 is provided with a check valve 10 in its discharge side permittinv flow of fluid through it towardsy the condenser 28 only. When the pump 22 stops at the end of each cycle of operation the refrigerant under pressure in the discharge line 24 and container 26 will gradually be equalized with he low pressure side of the refrigerating system due to reve'rse rotation of and leakage through the pump 22'which is not -equipped with valves, but the highpressure refrigerant in the condenser 28 andv receiver 30 will be prevented from being transmitted into the container 26 and housing 20 by the check valve 10. Consequently .at the beginning of the next cycle of operation of the pump 22 it will be initially pumping against a pressure substantially equivalent to that in the suction or lower -pressure side -of the system and there will .be

substantiallyrno head for the pump to pu'mp against upon initiation of operation. By suitably proportioning the chamber 26 to obtain the refquired` volume assurance may be had that the A m`otor 'driving the pump 22 will reach its normal speed of operation prior to a material or a nor-V mal operating'pressure existing in the discharge line 24. Shortly after the pump 22 has attained its normal speed of operation, if the chamber 26 is properly proportioned,` the pressure of the compressed refrigerant in the discharge line -24 will equal that in the high side of the system after which the check valve 10 -will lift and normal understood by those skilled in the art, to serve the same purpose as the usual compressor unloader found in refrigerating mechanisms and` provided for the purpose of permitting the motor .which drives the pump to attain its normal or substantially normal speed before the full burden of the pumping operationis placedu'pon it. The

provision of such a means is-of advantage in that a motor is not required to develop the torque that it would otherwise have to developif immediatelyy subjected to the pressure of the high side of the system upon initiation of its driving 'movement The result'is that` a less expensive motor may be employed with equally satisfactory section 84 provided with` three cylindrical-openings therethrough preferably arranged with their axes in a common planeas shown in Fig. fi and with adjacent peripheral portions lof adjacent openings in intersecting relation, the pcentral opening containing a gear 86 and the opposite end openings containing the gears 88.I OverlyingA the intermediate pumpbody portion 84 is a cap member 92 provided with an upwardly extending hollow boss 94 concentric with the gear 86 and the opening therefor and serving to rotatably receive therein an upwardly extending shaft 20 as by a press fit therein. ,Studs |0| threaded 96 the lower end of which is suitably fixed with respect to the gear 86 for transmitting driving movement thereto and the upper end of which has suitably iixed thereto the rotor 98 of an electric motor having a stator |00', the stator |00 being suitably received and secured within the upper and reduced end p0rtion of .the housing into the base plate 80 and extending through the pump b ody 84 and cover plate 92 serve tol secure these parts together. l

The leads to the' electric motor are carried through suitable connections indicated at |02 in Fig. 2 extending out through the walls of the housing 20 and hermetically sealed thereto in a l. conventional manner to prevent leakage of gas thereabout. As indicated in Fig; 1 and in accordance with conventional practice three leads, namely |04, v||l6 and |08 are provided-for the motor 98|00,`the leads |06 and |08 being con- -nected to conventional power. lines ||0 and ||2 through a conventional thermostatic switch structure l|| 4 arranged within` the cabinet 60 and operated ,by variations in temperature theref in for the purpose of controlling the cyclic operation of the compressor unit. The lead |04 which extends to a suitable starting-windingcircuit operation of the system will begin. The eect of the construction is, however, as will be readily (not shown) vextends through a. starting circuit reaker H6 in accordance with conventional practice and then to one of the'power lines ||0 or ||2.'

It will be understoodthat the gear's 86 and 88,- lie in-meshing relationship. The arrangement of the three gears 86 and 88 is such as to provide two independent gear pumps as far as suction eect is concerned. In other lwords the gear 86 and either one of the two gears 88 co-operate to form a gear pump in accordance with conresults. It may be noted, incidentally,'at this 4 point, that if desired an oil baille such as`12may be included in the chamber 26 for the purpose-of reducingthe otherwise normal ow of'lubricating oil with the refrigerant flowing through the evaporators, the oil separated out in such casel -being'carried back into the pump 22 during inoperative periods of the pump. due to the pressure equalizing action above described.

ventional gear pumppractice andthe gear 88 co-'operates with the other gear 88 to provide a 'dierent'gear pump in accordance' with conventional practice, except that the two pumps intermingle their discharges and are, therefore, to be' considered as one pump on the discharge side.v -Referring particularly to Fig. 4 if the gears are".- turning in the direction of the arrows indicated j gas or other uid will enter into the space between the gear teeth of the gears 88 .and Il nl? the point where the teeth of these gears are drawn out of meshing relationship with respect to eachother and willbe carried around lthe outer periphery of the gears, that ofvthen en Y fluid trapped in theteeth of thegal's l0 being Referring now to the remaining gures inthe 576 carried completely around the gear in a countertween the teeth of the gear 86 as such teeth 1 leave meshing relationship with the teeth of one of the gears 88 will be carried around in a clock'-i wisedirection as viewed in Fig. 4 and will be 3 squeezed out therefrom at the: point where the y lteeth of the gear 86 mesh with the teeth of the f other gear 88. Consequently with a gear pump of the type shown while the gear 88 and one of the gears 88 co-operate to provide a suction inlet which is entirely independent of the suction inlet formed between the gear 86 and the other ,Y

gear 88, nevertheless the uidwhich is drawn into the inlet formed between the gear 88 and one gear 88 will be carried around commingled with the gas or other uid which is drawn into the inlet between the gear 88 and the other gear 88 and consequently there would be no particular point in attempting to separate the discharge ports |34 and |42. In accordance with the above a suction inlet for the pump comprising the gear 88 and one gear 88 is formed by a drilled passage |30 drilled downwardly through the upper casting 92 of thepump, as indicated in Fig. 7, and meets the top wall of the pump body 84 at the point where the walls of the openings in the body 84 for the gears 86 and 88 intersect above .the plane, of the gear axes as viewed in Fig. 4 and this point of intersection of these walls is beveled off as indicated at |32 in Figs. 4 and 7 to provide an ample path for the ilow of iluid over the full width of the teeth of the gears 86 and 88 at this point. Iiiasmuch as the passage 38 is open to the inside of the housing 28, the

y opening |30 may be made as large as desired and may even be enlarged to the extent of eliminating all of that part of the top plate 82 overlying it except immediately over the area where the teeth of the associated gear 88 begin to and actually mesh with the teeth of the gear 86 as will hereinafter be brought out in connection with Fig. 10. Likewise such part of the body 84 surrounding such gear 88 not required for bearing on the periphery of the gear to maintain it in place may also be eliminated. The opposite point ofintersection of the walls of the opening in which the gears 86 and 88 are received is open to a blind opening |34 drilled downwardly in the bottom plate 80 of the pump and which terminates adjacent the lower end of a downwardly projecting boss |36 formed centrally oi the ybottom plate 88. The point where the walls of the openings for the gear 88 and the other` .gear 88 in the chamber plate 84 intersect adjacent the point where the teeth of these gears 88 and 88 leave `meshing relationship with respect to each other when turning in the direction indicated in Fig. 4 is operi to a blind opening |38, best shown in Figs. 4 and 8 drilled downwardly in the bottom platev 88 of the pump to a point' adjacent the lower face of the boss |38 and which thus serve as the second suction inlet for the pump. As in the case of the inlet |38 for the pump formed by the first pair of gears 88 and 88 the body at the point where the walls of the openings therein fonthe gear `88 andthe other gear 88 meet in alignment with the outlet passage |38 is beveled oi as at |48 to permit access of fluid entering through the inlet passage |38 `over the full width .of the teeth of the gears.

'I'he discharge side of the pump formedby the gears :88 and 8 8 provided at the points where the teeth of these gears enter meshing relationship with respect to each other whenrotating in the direction shown in Fig. 4 is provided with outlets in the form of blind openings |34 and |42 the intake pass drilled downwardly in the base plate 88 to points adjacent the lower end.of the boss |38 as best brought outl in Figs. 4, 'l and 8. As indicated in Fig. 6 within the lower portion of the boss |88 the lower ends of the discharge passages |34 and |42 are connected together by a pair of convergent horizontally directed passages |44 and |48, respectively, to a common outlet passage |48I connected in the particular illustrationA shown tothe discharge line 24 previously described. The suction connection |38 for the pump formed by the gear 86 andthe right-hand gear 88 is connected in the lower portion ofthe boss |88 with a transverse passage |50 suitably connected in the case illustrated with a suction line 58 for the evaporator 54. Because of the fact that the suction passage |30 for the pump extends upwardly through the cover plate 92 it will be apparent that it opens to the interior of the housing 28. The suction ducts 42 for Vthe evaporators 40 open into the interior 'of the housing 28 independentlynf one another through suitableV drilled passages |54 drilled upwardly through the base plate 88, body 84.y and cover plate 92 of the pump and the lower ends of which are respectively connected to the' suction lines 42 of the two evaporators 40. It will, accordingly. be understood in the construction shown that the refrigerant discharged from the evaporators 40 is carried into the interior of the housing 28 from which it is discharged through age |38 for the'pump formed by onepairof the gears 86 and 88. The pump thus formed by these two gears provides means for impressing the suction side of the evaporators.

other in the pump and being discharged therefrom in a single ystream by 'means of the passages best shown in Fig. 6. As previously mentioned this ability of the pump to provide for maintaining two entirely independent suction pressures of different values enables the evaporator 54 to be maintained under a normally lower temperature than that at which one or the other of the evaporators 48 is maintained.

The pump thus.described is novel in further respects than those heretofore brought out. For

instance it will be noted that the gears 88 are not provided with a shaft or journal about which K in manufacturing and once the gear is finished,

the holes being no longer necessary for its operation they are plugged as described. The gears 88 are maintained in proper meshing relationship with respect tothe gear 86 by peripherally bearing against the wallsof the corresponding openings in the body 84 land for this purpose such openings are made a fairly accurate fit with inch, or normally 11g of a respect to the circumferenceof the gears 88 and the ends of the teeth of the gears 88 are provided with unusually wide lands as indicated in Fig. 9, which thus provide ample bearing areas between the periphery of the gears and the walls helical gearor at the middle of a herring-bone of the openings in .which they are received. The j the base plate 80 and top plate 92 which would otherwise be required for the shafts of gearsf 88 and this permits manufacturing tolerances in the construction shown to be maintained at wider discharged, is allowed to escape to the opposite" limits than would otherwise be possible in quantity production.

The use of -a gear type 'pump as a compressor is old, but in all past usages, as far as I am aware,

the gear'pumps.designed for use as compressors have been at fault in being so designed that two mating gear teeth cannot possibly have involute curves throughout the length of their engagement;

Since the involute curvehv cannot extend below the base circle of a gear, it is obvious that in order to have an involute curve extend tol the root of a tooth or anywhere nearly to the root of the tooth, the gear must have a large number of teeth or be designed with an unusually large pressure angle. gear type compressors inthe past has been a gear of 10 to 16` diametral pitch having ten or twelve teeth. In a 16 pitch gear, the depth of engagement between the two gears is V8 of an inch above'` and below the pitch circle on each gear. These gears would have pitch diameters of one inch or less, even Awhen they are cut at a considerable helix angle. They have ordinarilyrbeen designed with a 14%"- Y pressure angle, but even if the pressure angle eter and a 20 pressure angle is only .9397",-

A common proportion `used in' gear. This is an erroneous conception, the fal-V lacy of which may be seen in considering a sectional view taken normal to the teeth of a pair of mating gears, having helical teeth. It will be seen that in addition to the clearance space at. Athe bottom of each tooth space, there is a considerable passage'allowed f or flow of the gas longitudinally of a tooth space, even whenboth teeth are properly engaged with a tooth of the mating Y gear. This means that thegas, instead of being compressed toward the end at which it is to be end of the tooth spaces of the two mating gears,

' and there is considerable ineciency in pumping for this reason. v

In the design of the gears for the compressor shown herein the faults of previous designs in theabove respects have been overcome by selecting proportions and sizes of gear teeth vto provide involute curves throughout the full depths of driving contacts between teeth on each of the pairl of gears; to provide for aminimum amount of clearance between the point of one tooth and the bottom of the space between teeth of the mating gear in providing for an overlapping of the arcs of working contact of successive teeth; and in using straight spur gears instead of helical gears.

A simple mathematical formula for providing involute curves throughout the full depths of driving contacts between teeth on each of the pair of gears is that the base circle radius of either gear must not exceed the radial distance from the center of thev gear to the point of intersection of the outside diameter of the gear mated therewith in running position and one of the internal tangents common tothe base circles of the two whichgure is the cosine of 20, and the base circle diameter is the product of the pitch diameter and the cosine of the pressure angle.

With a gear of this type, the involute curve can 'extend onlypabout .030" below the pitch circle. As vtrue of each gear, it provides a depth ofonly .0 60" out of the total working vdepth of the teeth in which the mating teeth can possibly engage each other on involute curves.

Another ault o f all gear pumps employed as refrigeration. compressors in the past, as far as I am aware, is that the usual clearance commonly provided in all types of gearing has been allowed at the bottoms of tooth spaces. This clearance is provided for in the making of stock gear cutters and hobs, but is undesirable in a.

pump which is to be used for the purpose of compressing a gas because it leaves a dead space of compressed gas which cannot be forced out through the discharge port and the work gears. The two popular pressure angles used on gears are 141/2 and 20, and the cosine is smaller inside of the bottom diameter circle. vOn the gear 86 at the right of Fig.9, this condition is even more, pronounced. The proportions selected for this view are fifty-nine teeth on the right-hand or driving left-hand or driven gear 88. The outside diameters of the two gears are the sameandthey are assumed to have beencut with \the same hob, which is specially designed to allow a minimum -of clearance between the points of the teeth and the bottoms of the spaces between the teethof the mating gear. Since the base circular pitch must be the same on the two gears, the base circle of the nity-nine tooth gear 86 is 5%1 of the base' circle'of the sixty-one tooth gear 88. The depth of teeth is the same on the. two gears. Due to A of the proportions that have heretofore been used in gear type compressors designed for refrigerating systems. It is not necessary vto go to the extreme illustrated by Fig. 9, but it is necessary that the' base circle-fall inside of the smallest circle at which a tooth contact is made on either gear. In other words, on either o f the two straight lines tooth space, and compressed at one end ot the IBI which form the internal tangents of the two gear 86 and sixty-one teeth on the Thisbase circles, there must always be one and there between involute curves of mating teeth. Inorder to arrive at the number of teeth necessary to meet this requirement, and this regardless of whether the gears are of equal diameter, the base circular pitch, which must be identical in both gears, must be less than the length of that part -should be two or more points` of driving contact direction so as to bring one of the valves |16 of an internal tangent of lthe two base circles of the pair of mating gears cut off bythe outside diameter circles of the two gea It is desirable which requires that the base circular pitch of the gears be less than half of the above defined portion of the internal tangent.

In the example shown in Fig. 9, the outside diameter of each gear blank is thatof a normal sixty tooth gear. Because the driving gear 86 is cut with fifty-nine teeth, its base circle is reduced in diameter so that the tooth flanks are formed by parts of the involite curve considerably removed from the base circle. On the sixty-one tooth driven gear 88 shown at the left of Fig. 9, having an outside diameter which would be normal for a sixty tooth gear, the base circle is still inside of thebottomdiameter circle in this example, but the tooth fianks are developed by portions of the involutecurve which are much closer to the base circle. This' means that during the process of generating the two gears from the same hob, the gear blanks are driven at different ratios to the hob rotation. When the two gears thus generated are engaged with each other,- it will be found that the pitch circle of the sixtyone tooth gear 88 falls nearer to the outside diam- ..eter`, whereas the pitch circle of the fifty-nine tooth gear 86 falls nearer to the bottom diameter.

"to have two teeth in working contact7 at all times into sealing relation with respect to the corre'- spondi-ng passage |54, the other valve |16 is lifted fron its passage |54 so as tov open the latter passage to the interior of the lcasing 20.

4The rocker |14 with its valves |16 is caused to alternately pivot inopposite directions by means of the following mechanism; An arm member |18 is pivotally connected by means of a pin |80 to a side face of the casting 82 of the compressor for swinging movement in a vertical plane. -The upper end. of the arm |18 is bent' laterally and then downwardly to provide a downwardly directed projection |82. The rocker |14 is provided with an upwardly directed projection |84 midway between the ends thereof and with the point -thereof lying in a plane including the axis of the shaft |12 and arranged in substantially perpendicular relation with respect "Ito the general plane of the rocker |14; A Icoiled 'Ihe design of this pair of gears as before outlined would accomplish its purpose with either one of the two acting as the driver, but for the purpose of this design' the fifty-nine tooth gear 86 is employed as the driver and the sixty-one tooth gear 88 as the driven gear for reasons previously described. It will be noted from Fig. 9'

that the lands at the tops of teeth on the sixtyonetooth gear 88 are greater than the lands at the 'tops cf the teeth on the nity-nine tooth gear 85., This is a result of the method oi' gen- Jdesirable in providing a more continuous flow,

of compressed refrigerant to theondenser and breaking up the sound of gas discharges from the compressor. Likewise, the/suction impulses ocl cur alternately, there being 118 suction impulses in the two separate suction passages and '118 discharge impulses directed into the 4one discharge passage |48 leading to the condenser per revolution of gear 86. 1

In order to operate the valve mechanism indicated generally at 44 in order to alternately open and close the suction lines 42 for thefjevaporators 40, the boss 84 for the top plate 92 of the pump is provided with a laterally extending boss |10 best shown in Fig. 3. A shaft |12 arranged with its axis in perpendicular relationship to the l axis of the shaft 86 is fixed within the boss |10 and projectslaterally outwardly therefrom. A

rocker element |14, best shown in Fig. 5, is vplv,-

otallymounted upon the shaft i12 in overlying spring |86 extends between and is maintained under compression between the projections |82 'and |84. The arm |18 is provided with an elongated aperture |88 therein within which aperture is received a cam |90 mounted for rotation therein in a' manner which will hereinafter be fully explained. Upon rotation.` of the cam from the position indicated in Fig. 5 the point of the cam in turning will eventually Vstrike against 4the left-hand side of the sloty |88 and cause the arm |18 to be pivoted in acounter-clockwise direction of rotation, as viewed in Fig. 45, until the movement of the arm |18 to the left o'r in a counter-clockwise direction as viewed in Fig. 5

being limited by the right-hand wall of the slot |88 striking against the cam |90. Continuing rotary movement of the cam |90 will thereafter gradually cause the arm |18 to pivot in a clockwise direction of rotation about its pivot pin4|80 until the point of the projection |82 passes to thev right'of a'plane including the axis of the shaft |12 and the point of the projection |84 at which time the force of the spring |86 will cause the parts to resume the position shown in Fig. 5. As will be apparent this mechanism constitutes a snap mechanism operated through rotation of the'cam |80 to alternately cause the valves |16 to be snapped between open and closed position with respect to their respective passages |64.

In order to operate the cam |90 so that the time ci activity of each of the evaporators 40 will be suilicient to cause freezing of a desired thickness of ice or a desired maximum limit of frost accumulation and to insure melting of the ice or frost thus formed during each inoperative period of each of the evaporators 40 the following mechanism is provided.v Secured on the shaft 96 immediately above the boss 84 by means of 'a pin 20l`passingthrough the hub portion thereend portion only of a conventional Hindley worm.

The worm wheel 202 is arranged in meshing relationship with a gear 204 arranged with its axis in a horizontal plane and rotatable with its shaft 206, best shown in Fig. 3, having bearing in a suitable boss 20B formed on the upper face of the top member 92 of the pump 22. The opposite l0 end of the shaft 206 is formed to provide a single thread worm 2I0 thereon. It will be noted from an inspection of Fig. 3 that the bore in the boss 208 for the shaft 206 is enlarged at the Worm end of the shaft andthe corresponding end of the l5 worm 2I0 projects into such enlarged bore portion for a purpose which will hereinafter be more clearly brought out.

The projecting end 'of vthe worm 2I0 lies inmeshing relationshipwith a helical gear or worm The endupon the outer end of the fixed shaft |12 out- 30 wardly of the arm I'l8and to which gear or Worm wheel 220 the cam |90 is fixed for equal rotation therewith. The train of gears thus provided between the shaft 96 of the motor 98|00 and the pocket. 232 is filled with oil. The worm wheel 204 in rotating carries oil upwardly therewith4 and into contact with a worm 202, thereby to lubricate the rubbing faces between the worm 202 and worm wheel 204.l Further, as illustrated in Fig. 2 the periphery of the worm' wheel 204 extends into almost contacting relation with respect to the outer surface of the boss 94 on the cover plate 92 and adjacent this point of almost contact the boss 94 is provided with a downwardly vand inwardly, extending passage 236 the edgesof-which are adapted to wipe off lubricant from the periphery of \thevworm 204 which as will be understood will be rotating at a 4fair speed of rotation and, therefore, tendto throw the oil thereon to the outer periphery thereof, and in this manner oil is carried to thebearing inthe boss 94 for the shaft 96. yThe oil passing into the passage 236 will, of course, lubricate the upper bearing of shaft 96 and be carried on downwardly into the pump whereby to effect lubrication of the wearingf'surfaces thereof. Additional- 1y, it will be understood, of course, as in all conventionalconstructions the refrigerant will carry a certain amount of entrapped lubricating oil along with it in circulating through the system and this, together with the movement of the parts in the housing 20, will tend to create a certain amount of oil vapor yin the housing 20 which will be drawn into the compressor 22 through the inlet passage for that portion of the compressor formed by the gears 86 and 98 and thus the gear 220 to which the cam |90 is secured A35 preferably provides a gear reduction of such nature that the 4cam |90 will make one complete revolution during each sixty or more minutes of continuous operation of the motor 98-I00. The

gure selected in the design shown is eighty to obtain any desired ratio of movement between the driving motor andthe cam |90.

Lubrication of the moving parts of the cpmpressor unit is accomplished in the following manner. As in substantially all refrigerating systems a quantity of lubricating oil is introduced into the system and in the present case the lower part of the casing 20 provides a reservoir for the main body of lubricatingV `oi1 which is indicated at 230. The lubricating-'oil 230 is of such a depth as to immerse the lower portion of the worm wheel 2|2- therein so that the worm wheel in rotating will carry oil up with it into contact with the worm 2I0. The pitch of the worm 2I0 is preferably such in relation to its direction of rotation that oil deposited thereon will tend to be carried towards'the top ofthe sheet as viewed in Fig. 3 and into the enlarged portion of the bore for 'the shaft 206. The oil which is carried into the bore in the boss 208 for the shaft 206 will, of course, provide lubrication 55 for the shaft 206. Additionally it will be noted from an inspection of Figs. 2A and 3 that a pocket 232 is provided in the upper face of the casting 92 of the compressor into which pocket 232 the The boss 208 is provided with an oil lead 234, in-

" dicated in Figs. 2 and 3, which leads from the `Jjunction of the large and smallportions of the there 1n the boss zus for the' shaft zus-into the` pocket 23 2.fand thus provides .a` means whereby 75 lower portion of the worm wheel 204 projects.

provide an additional supply ofv lubricant for the working parts of the pump.

In Fig. 10 a modification Vof the above described motor compressor unit is shown illustrating' a preferred construction thereof not particularly designed for use in` connection with parallel evaporators such as the evaporators- 40 in the previous views. As will be apparent under such circumstances, it i's not necessary to provide any control means for the alternated connection of a pair of suction passages with the interior o f the casing, and consequently the gearing previously described for the operating cam 90 may be dispensed with, but in such cases a diierent type of oil system must be provided. J

Referring to Fig. 10 in which parts corresponding to the parts previously'described are indi- .cated by the same numerals except that such numerals bear a, prime mark, the casing 20 instead of being welded to the base plate as in the previous construction is provided in an outturned marginal flange 250 voverlying the peripheral portion of the hase plate 80' with'v the interposition of a suitable gasket therebetween.;

ends of coil springs 258. are threaded. The coil springs 258 serve as a resilient 'support for the motor compressor unit.

In this case the base 80' instead of having a flat upper surface is provided with a raisedcen, tral portion 259 providing an Voil sump between its periphery and the casing 20' in which the oil 2I0 is received. It will be noted that the level p in connection with the preceding gures.

of the oil 236' isbelow the upper edge of the `portion 259. The tube 2,62 having one end open to the oil 230' in the `sump extends upwardly therethrough an'dprojects through the wall of the tube 260 where its end is bent 1n the direction of the refrigerant flow therethrough, and the walls of the tube 260 in approximate transverse alignment withthe upper end of vthe tube 262 is preferably compressed inwardly a's at 264 to effect a venturi so that the iiow of Arefrigerant through the tube 260 will create. a'. sufficient low pressure at the discharge endof the tube 262 to cause oil to be drawn through the 'screen 266 and up from the sump to be discharged into'the tube 260.

The boss 94' of the top plate 92 of the pump is provided with an upward opening depression 268, the bottom portion of which is connected by Ta passage 210 in the boss 64' with lthe surface of the shaft 96' therein. The end of the tube 260 is extended over the depression 268 so that'oil discharged from the tube 260 with the refrigerant will be deposited in the depression 268 and, therefore, be led'to th/bea'ring surface for the shaft 66' and be carrie thereby downwardly into the gear section of the pump and the lower bearing .for the shaft 66' 'in the base plate 80. Although a suction port similar to port |30 previously described may be provided for conducting refrigerant from the interior of the casing 20' to either or both pairs ofthe gears 86' vand 86', in the present case a portion.' of the top plate 62f is broken away so that a relatively large area of the top of one of the gears 88', as at 212, is exposed directly to the space withirrthe housing 26', and the refrigerant within the housing 20" is, therefore, fed to the space between` the teeth of the gear 68' directly instead of through a separateLv formed suction passage. Wherethe t gear 86 and only one gear 86 is employed, and

the tube260 forms the sole suction conduit for the refrigerating system, all of the refrigerant circulatedl in the system will be introduced to the pump through the cut-away portion 212 de scribed. Where two separate evaporators are employed, for instance, as inthe case where the evaporator 254 and only one of the evaporators 40 previously described, or asimilar arrangement, the suction tube 260 will, of course, be connected to only one ofthe evaporators, andthe suction line for the otherevaporator willbe brought `up through the bottom of the base plate 80' in a manner equivalent or similar to that described One feature of the present invention is brought out in Fig. 10, and that is i connection with means for preventing'excessive amounts of lubricating oil from passing through the compressor. This feature comprises the provision of an opening such as 214 leading through the wall jof the compressor, shown in Fig. l0, as through a wall of the body 84 'and' opening to'the lower peripheral portion of that gear 88' which cooperateswith the gear 66 to draw refrigerant from the interior of the casing 30 and.Y thereafter compress it. The provision of 'such' an opening 214 would not be applicable to the pump formed by the gear 88' and gear 86 drawing the refrigerant through the bottomplate independently of the casing 20' where the casing 26' also l serves as a part of a refrigerant ow path for a separate evaporator, but. where the`compressor comprises merely a pair of gears having a single suction port, or three gears having theirsuction ports combined then all ofethe gears-may be f provided. with openings equivalent to the openings 214. The openings i214 may-connect with the lower tooth portions of such gears and preferably extend downwardly from the outery edge of the co-.operating gear so that lubricating oil trapped between the teeth of the gears and carried by gravity to thelower edges thereof will be either wipd on or thrown olf under centrifa simultaneously exert independent suction effects therethrough, a pair of evaporators, means for delivering refrigerant from said fcondensing means to said evaporators in parallel including refrigerant regulating means controlling the ow of refrigerant to one of said evaporators and to a second refrigerant regulating means in series with the first mentioned regulating means and with the other of said evaporators, a suction duct connecting one of said evaporators to one of `said suction ports, and a separate suction duct connecting the other of said evaporators with the other of said suction ports.

2. In a refrigerating mechanism, in combination, refrigerant condensing means provided withl independent suction ports and adapted to simultaneously exert independent suction `effects therethrough, a pair of evaporators, means for delivering refrigerant from said condensing means to said evaporators in parallel including refrigerant regulating means controlling the flow `of refrigerant to one of said evaporators and to a second refrigerant regulating means in series with the first mentioned regulating means i 0f one of said suction ducts.

and comprising a weighted valve device connected with the other of said evaporators, a suction duct connecting one of said evaporators to one of saidisuctlon ports, and a separate suction duct connecting the other of said evapo# rators with the other of said suction ports.

3. In-a refrigerating mechanism, in combination, a sealed housing, a compressor, a part of said compressor forming a closure for said housing, said compressor having a pair of independent suction ports one drawing vapor from inside of said housing and one located in a wall of said compressor at a point exposed outside of said housing, and a pair of independent suction ducts for delivering refrigerant to said suction ports, the interior of said housing forming a portion 4. In a ref rigerating system,.a compressor so constructed and arranged that gas from the discharge side may return to the suction side thereof after said compressor has stopped, a motor for driving said compressor, a condenser into which said compressor is adapted to discharge compressed refrigerant, a duct connecting said compressor and condenser for the passage of said refrigerant, and a check valve located in said duct to prevent'flow of vapor from said condenser to said compressor in a reverse direction,

said duct being so constructed and .arranged in that portion thereof between said compressor and said check valve as to provide a sufficient volume for compressed refrigerant to permit said motor upon starting to approximately reach its running which said compressor is adapted to discharge compressed refrigerant, a duct connecting said compressor and condenser for the passage ofsaid refrigerant, a check valve located in saidv duct to preventow of vapor from said condenser to said compressor in a reverse direction, saidduct being so constructed and arranged in that portion thereof between said compressor and said check valve as to provide sufficient volume for compressed refrigerant to permit said motor upon starting to approximately reach its running speed before the pressure of the refrigerant delivered by the compressor to said portion of said passage during said starting equals the pressure of the refrigerant in said condenser, andmeans for trapping oil in an intermediate portion of said duct portion in such a manner that it will be returned to said compressor during the idle periods of said compressor.

6. In a refrigerating system, a compressor and a motor, a gas tight housing enclosing said ccmpressor and motor, said housing having a pair of suction passages leading thereinto, valve means for alternately opening and closing one of said l passages as it closes and opens the other of said passages, and means driven by said motor actuating said valve means, said compressor having an Yinlet port open to the interior of said housing.

7. In combination with a. refrigerating system, a compressor comprising a housing, a train of three gears in said housing, means for driving said gears, said housing providing discharge ports located adjacent the points where the teeth of mating gears begin to'engage and suction ports for introducing gas between the teeth of said vgears, a pair of evaporators, meanslconnecting said evaporators with said discharge ports, means connecting one of said evaporators with one of said suction ports, and means independent of the last mentioned means connecting the other of tion passages for conducting vaporized refrigerant from said evaporators, one connected to each of them, valve means for alternately opening and closing one of said passages as it closes and opens the other, and power means for actuating said valve means, said power means deriving its energy from a source enclosed in said housing.

11. In a refrigerating system, a motor-compressor assembly, a sealed housing enclosing the moving parts of said assembly, a plurality'of suction conduits through which vapor may flow under suction produced by the compressorzof said assembly, and means within said housing operable automatically as a result of the functioning ofv said system for intermittently stopping the ow of vapor through one of said conduits for a period of time considerably longer than that of a revolution of said compressor.

being reversible during idle periods under the influence of refrigerant under pressure on its discharge side whereby to enable it to relieve itself of said discharge pressure during idle periods.

13. In a refrigerating system, a rotary compressor of the displacement type, a motor for driving said compressor, a sealed housing enclosing the moving parts of said motor and compressor and adapted to contain a refrigerant circulated in said system and a lubricant for said -moving parts, and centrifugal means in said c'ompressor for separating said lubricant from said refrigerant.

14. In a refrigerating system,\a motor compressor assembly comprising a motor and a compressor and a. driving connection therebetween, a

l gas-tight housing enclosing said driving connecsaid evaporators with the other of said suction ports. f

8. In a refrigerating system, a. compressor, a motor having a driving connection with said compressor,`a sealed housing enclosing said driving connection, a plurality of evaporators,jsuction conduit means connected with the interior of said housing and with said evaporators, means for selectively connecting said evaporators with the suction side of said compressor through said conduit means, and powermeans driven by said motor for actuating said. selective connecting means.

9. A compressor, an enclosure forvsuction gas connected therewith, valve means in said enclosure, and means for actuating -said valve means with mechanical power derived from'the opera- --tion of said compressor in a cycle materially longer than that of a compressor revolution. e 10. AIn a refrigerating system, a pair of evaporators, a motor-compressor unit, a sealed housing enclosing' said unit, means forming a pair of suc-` tion and the moving parts of said motor and compressor, a` refrigerant suction duct leading to said housing, a refrigerant suction duct leading to said compressor and open to the interior of said housing, and a refrigerant suction duct separated from both aforesaid suction passages and leading directly to a separate suction port of said compressor at an area thereof exposed outside of said housing.

15. In a refrigerating mechanism, in combination, a compressor, a motor, a driving connection between'said motor and said compressor, a housing surrounding said motor and connection and sealed to said compressor with a surface of said compressor exposed exteriorly of said-housing and and said housing having va suction passage vopening through a wall thereof adapted for connection with a source of flow of refrigerant whereby to admit refrigerant therethrough into the interior of said housing, whereby said interior of said housing forms a part of a suction passage v.ber tween said rst suction portand the second mentioned source of ow of refrigerant.

-16. In a refrigerating mechanism of the class parallel evaporators of common means for ef-i fecting a iiow of refrigerant therethrough com-4 e pri'sing a compressor, a motor, a driving connection between said compressor and motor, a housing surrounding said motor and connection and sealed in gas-tight relation to said compressor leaving a face of said compressor exposed exteriorly of said housing, said compressor having a iirst suction port open to the interior of said housing and said housing having a port in the wall thereof for receiving the iiow of refrigerant from said high temperature evaporator whereby the interior of said housing forms a part of the refrigerant passage between said high temperature evaporator and said suction port, said compressor having a second suction port opening onto the exterior of said face for direct connection to the other of said evaporators, and said compressor having a discharge port opening onto said face.

17. In a refrigerating system, a motor compressor unit, a chamber associated therewith, a plurality of evaporators each having a` suction passage opening into said chamber, valve means in said chamber and valve actuating means for 18. In a refrigerating system, in combination,

a cabinet, a freezing compartment and a food storage compartment in said cabinet, a separate evaporator for each of said compartments, re-

frigerant compressor means, a connection between said means and said evaporators for delivering compressed refrigerant from said means to both of said evaporators, means in said connection for maintaining said vevaporator for said freezing compartmentat a higher temperature than said evaporator for said food storage com-v partment.

19. In a refrigerating system, in combination, 

